At What Age Do Dogs Stop Growing? How Big Will They Get?

Puppies seem to grow up so quickly and we find ourselves wondering when will it stop and how big will they eventually become?

If you’re staring at your pup and wondering just how much bigger they are going to get, today we will answer the question “when do dogs stop growing” and at “what point are puppies considered adult dogs?”.

Le’s Start With Puppies

Puppies typically start out being extremely dependent on their mothers and being very delicate and fragile, as most baby animals begin their lives.

At about two weeks old, a puppy’s eyes will open for the first time, and at three weeks, they begin to gain increased mobility.

By the time they hit two to three months of age, they may begin to encounter new experiences that can cause nervousness or anxiety, thus needing positive reinforcement from their mothers or owners to gain confidence.

Between 3 and 6 months is what we consider the “toddler” age of puppies. They begin to become much more active and excitable, start teething and chewing on things and begin to get up to all sorts of mischief.

Then, between 6 and 12 months, a puppy experiences what we might consider a “teenage” phase, where they reach the height of their mischief and energy and may begin to sexually mature as well.

From here on out, when a dog actually stops growing for good depends on a number of different factors.

Different Breeds, Different Growth

Different breeds of dogs have different rates of growth, usually dependent on the size they are expected to be when fully grown. Essentially, the smaller the dog, the quicker they will reach adult size.

This goes for mental maturity as well.

Mental maturity refers to the age at which dogs cease their tendency for reckless, more destructive behavior that humans may attribute to “adolescent” or “teenage” behavior and settle into a more relaxed and peaceful state.

If you have two dogs of different breed sizes you may notice that the smaller one seems much more mentally mature than the bigger one. All dogs have different aging duration depending on the type of breed.

At What Age Do Dogs Stop Growing?

Here’s a general breakdown of how long individual dog breeds take to reach their full-grown size, as well as a general timeline of the expected weight of each breed size at different ages so you can keep your eye on your pup’s developmental progress:

Small Toy Dog Breeds

Very small dog breeds, such as the famed Chihuahua, will reach their adult size at approximately 10 to 12 months old.

Medium-Small Dog Breeds

These breeds will grow to their full size by between 12 and 15 months of age and usually will arrive at their adult weight at around 18 months old. This applies to breeds like beagles and toy poodles.

Medium-Large Dog Breeds

These breeds will grow to their full size at the age of around 18 months old, though it will take them until about 24 months to hit their full weight. Breeds such as these include Labrador and golden retrievers and Collies.

Large Or Giant Dog Breeds

The largest dogs take the longest to grow – a whopping 3 years to hit their adult weight – but also only take 18 months to grow into their paws.

For giant breeds such as Great Danes and Mastiffs, the easiest way to find out when they have fully reached their adult size is by their paws.

when do dogs stop growing

As puppies, their paws often appear disproportionately larger than the rest of their bodies. Once they reach adult size, their proportions will look more even and balanced.

Keep in mind that these are general timelines and that this differs by the individual dog and also specific breed. You should check with your vet for a more reliable timeline.

What About Mixed Breeds?

Is it possible to determine when a mixed-breed puppy will reach its full size, and how big it will be then? Unfortunately, there is no real way to know for sure.

Even if you are 100% certain of the puppy in question’s genetic makeup, there is no way to do more than present a rough estimate of the dog’s resulting size and growth rate.

A vet can attempt to give you an intelligent guess on these factors, but there is no way to ensure its accuracy.

This is even more true for dogs whose genetic background you are unaware of, or for dogs that have been a product of generations of mixed breeds. In this case, your best bet is to either have a DNA test done.

If you prefer not to but would like to know when your dog has reached adult size for sure, you can have an x-ray done when the dog has grown to what you think may be its adult size.

This x-ray will check if the growth plates have closed, and if they have, then your dog is fully grown.

Ensuring Healthy Growth

Healthy growth is determined by a number of different factors, and it’s important that you work to ensure that your pup grows to its healthiest size and weight.

Speak to your vet about weight and size goals to meet or simply about what to expect in size and weight, and if your dog makes a large deviation from these expectations, be sure to re-examine some of the factors that could be affecting this.

Here are some areas to focus on to ensure healthy growth:


If your dog continues gaining weight well past its projected healthy adult weight, or if it never quite seems to meet the weight it is supposed to, then this could be due to unhealthy eating habits – whether that is overeating or undereating.

Regular vet check-ups are mandatory for a growing puppy and should ensure that you are always aware of what is going on with your pup’s growth, but you can check this out yourself at home, too.

And don’t give your puppy rawhide, give them something else to chew on since they like very much to chew on things.

To ensure that your pup is neither under nor overweight, regularly check its body to make sure of the following:

  • Ribs are not visible
  • Ribs can be felt
  • A waist is defined and visible

If your dog seems to be underweight, add an extra meal at a relatively equal interval into the day. This is a much better option than making existing meals larger.

For slightly overweight dogs, decrease the amount of food given at each meal by a small amount for a week or so, then slowly revert back to the original amount.

For heavily overweight dogs, decrease the amount of food given on a more long-term basis and encourage more gentle movement and play.


If you neuter a dog before it reaches its full growth, then you may end up with a dog who grows a little bit bigger than expected.

This is because a pup’s sex hormones are responsible for telling the dog’s body when it is time to stop growing. The desexing process will cause these hormones to be unable to communicate that information.

This is why it’s advised that you wait until your pup is fully grown before going through with neutering.

In fact, multiple studies have proven that dogs who are neutered before they have reached full size are more likely to develop joint, hip, and ligament problems later on in life.

After neutering, you should also monitor your dog’s eating habits since they are mostly carnivores they will like to eat as much meat as possible, for a few days as some experts believe that desexing can change a pup’s appetite.

Though this is not a universally agreed upon fact, it’s worth keeping in mind.

Limit Heavy Exercise

Exercise is great and playtime is fantastic for puppies.

But teaching more strenuous activities such as leaping, jumping, going through obstacle courses or participating in dog agility runs should be reserved for when a pup is fully grown.

This is because puppies still have open growth plates, which can be damaged by strenuous activity.

If you really want to train your puppy, take them to the vet once you think they are fully grown and have an x-ray done to see if those growth plates have closed.

When in doubt, always ask your vet when you can begin training a dog for agiler and physically demanding exercises and activities.

I hope you liked our answer to your question “at what age do dogs stop growing?” and hope to see you soon.

Sources and References:

  1. Aging in dogs –
  2. Dog breeds –
  3. When do they stop growing –

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